Deformation of Olivine at Mantle Pressure using D-DIA

Journal Article · Sun Jan 01 04:00:00 EST 2006 · European Journal of Mineralogy

DOI:https://doi.org/10.1127/0935-1221/2006/0018-0007· OSTI ID:959669

Li, L

Knowledge of the rheological properties of mantle materials is critical in modeling the dynamics of the Earth. The high-temperature flow law of olivine defined at mantle conditions is especially important since the pressure dependence of rheology may affect our estimation of the strength of olivine in the Earth's interior. In this study, steady-state high-temperature (up to 1473 K) deformation experiments of polycrystalline olivine (average grain size ? 10 ?m) at pressure up to 9.6 GPa, were conducted using a Deformation-DIA (D-DIA) high-pressure apparatus and synchrotron X-ray radiation. The oxygen fugacity (fo2) during the runs was in-between the iron-wustite and the Ni/NiO buffers' fo2. The water content of the polycrystalline samples was generally about 150 to 200 wt. ppm but was as low as 35 wt ppm. Typically, 30 % strain was generated during the uniaxial compression. Sample lengths during the deformation process as well as the differential stresses were monitored in situ by X-ray radiography and diffraction, respectively. The strain rate was derived with an accuracy of 10?6 s?1. Differential stress was measured at constant strain rate (?10?5 s?1) using a multi-element solid-state detector combined with a conical slit. Recovered specimens were investigated by optical and transmission electron microscopy (TEM). TEM shows that dislocation glide was the dominant deformation mechanism throughout the experiment. Evidence of dislocation climb and cross-slip as active mechanisms are also reported. Deformation data show little or no dependence of the dislocation creep flow with pressure, yielding to an activation volume V* of 0 {+-} 5 cm3/mol. These new data are consistent with the high-temperature rheological laws at lower pressures, as reported previously.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 959669
• Report Number(s): BNL--82655-2009-JA
• Journal Information: European Journal of Mineralogy, Journal Name: European Journal of Mineralogy Vol. 18; ISSN 0935-1221; ISSN EJMIER
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ACCURACY
BUFFERS
COMPRESSION
CREEP
DEFORMATION
DIFFRACTION
DISLOCATIONS
GRAIN SIZE
OLIVINE
OXYGEN
PRESSURE DEPENDENCE
RHEOLOGY
SIMULATION
STRAIN RATE
STRAINS
STRESSES
SYNCHROTRONS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY RADIOGRAPHY
national synchrotron light source